Corynebacterium, especially, Corynebacterium glutamicum, is a Gram-positive microorganism which is widely used in the production of L-amino acids. Of L-amino acids, L-lysine is applicable in a variety of industries, including animal feedstuff, pharmaceutical and cosmetic industries. For use in these industries, typically, L-lysine is produced by fermentation using Corynebacterium strains.
Corynebacterium strains anchoring enhanced genes involved in lysine biosynthesis and methods of producing L-lysine are well known in the art. For example, U.S. Pat. No. 6,746,855 discloses corynebacteria strains with an enhanced lysE gene (lysine export carrier gene), to which genes selected from the group comprising a dapA gene, a lysC gene, a pyc gene and a dapB gene are additionally introduced, and a method for the production of L-lysine by cultivating the strains. U.S. Pat. No. 6,221,636 discloses a coryneform bacterium carrying a recombinant DNA comprising a DNA sequence coding for aspartokinase, in which the feedback inhibitory activity of L-lysine and L-threonine is substantially desensitized, and a DNA sequence coding for a diaminopimelate decarboxylase.
Nowhere are Corynebacterium spp. which show higher activity of the six enzymes involved in the biosynthesis pathway of lysine, that is, aspartate aminotransferase, aspartate kinase, aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase, dihydropicolinate reductase, and diaminopimelate decarboxylase, than the endogenous activity thereof, mentioned in any document published prior to the present invention. Furthermore, Corynebacterium spp. that show more than the endogenous activity of pyruvate carboxylase in addition to the six enzymes are not found in any documents published prior to the present invention.